Adenomyoepithelioma of the breast with malignant transformation and repeated local recurrence: A case report

BACKGROUND Adenomyoepithelioma (AME) of the breast is a rare type of benign breast tumor. Many AMEs show benign behavior, but reports of the malignant type are rare. We present the case of a patient with AME with repeated local recurrences and further malignant transformation. CASE SUMMARY A 53-year-old woman visited our hospital with a 16-mm palpable mass in the right breast. A core needle biopsy was performed. The pathological diagnosis was AME. Lumpectomy with a safety margin was performed without axillary lymph node dissection (ALND). Two years later, local recurrence developed, and the patient again underwent lumpectomy with a safety margin. The pathology showed malignant AME, and the margin was negative. Eight months later, local recurrence developed again in the same location, and a total mastectomy was performed without ALND. The pathological diagnosis was malignant AME. The patient was disease-free for three years posttreatment. CONCLUSION The treatment of AME requires caution, as it may exhibit repeated recurrences after local excision as well as malignant transformation.